Draftsman&#39;s and mechanic&#39;s instrument



May 6, 1952 F. P. HOPFELD Filed April 12. 1949 2 Sl-IEETS-SHEET l Patented May 6, 1952` DRAFTSMAN S AND MECHANICS INSTRUMENT Fred P. Hopfeld, Elmwood Park, Ill., assignor to Grand Specialties Company, Chicago, Ill., a corporation of Illinois Application April 12, 1949, Serial No. 87,025

2 Claims. (Cl. 33107) This invention relates to draftsmens and mechanics instruments and particularly to instruments which enable the magnitude or extent of a dimension or a fraction thereof to be readily determined.

Heretofore, Iso-called decimal equivalent charts have been utilized by draftsmen, designers, mechanics and the like. Such charts usually ineluded, in tabular form, the more common dimensions expressed fractions and the decimal equivalents of such fractions have been associated therewith on such charts. However, with such charts, when a draftsman or the like desired to determine the precise extent of a dimension it has -been necessary to resort to a graduated scale or the like, since such charts have not embodied any way by which the magnitude or extent of a particular dimension could be determined. Moreover, in instances where it has been desired to inscribe, for instance, a circle of a predetermined diameter, it has been necessary to resort to a graduated scale or the like to set a compass, divider or the like at proper radius of the desired circle. Hence, while so-called decimal equivalent charts of the aforesaid nature have been useful, it has heretofore been necessary to employ a graduated scale or the like along with such charts in the use thereof.

In View of the foregoing it is the primary object of my invention to not only afford a socalled decimal equivalent chart but to associate with each of the dimensions included in such a chart a representation of the magnitude or extent of each particular dimension so as to thereby facilitate the setting of a compass, divider or the like in the amount of a selected dimension.

Yet another object of this invention is to so arrange an instrument of the aforesaid character that the radius of a particular circle may be quickly determined so as to thereby facilitate the inscribing of such a circle.

A further object of my invention is to so arrange an instrument of the aforesaid character that dimensionsof certain articles, such as. for example, the length of bolts, rivets and the like, may be quickly determined in a novel and expeditious manner.

Other and further objects of the present invention will be apparent from the following description and claims and are illustrated in the accompanying drawings which, by way of illustration show a preferred embodiment and the principle thereof and what I now consider to be the best mode in which I have contemplated applying that principle. Other embodiments of the invention embodying the same or equivalent principle may be used and structural changes may be made as desired by those skilled in the art without departing from the present invention and the purview of the appended claims.

In the drawings:

Fig. 1 is an elevational View of an instrument embodying my invention and drawn to a double scale;

Fig. 2 is a fragmentary sectional view taken substantially along the line 2-2 of Fig. 1;

Fig. 3 is a view similar to Fig. 1 showing a modified form of my invention; and

Fig. 4 is a View similar to Fig. 1 showing another modied form of my invention.

The instrument embodying my invention illustrated in Figs. 1 and 2 of the accompanying drawings embodies a substantially rectangular plate desirably formed of metal but which may be made of wood, hard: rubber or a so-called synthetic resin or like material. On one of the flat faces of this substantially rectangular plate 3l fractional dimensions and the decimal equivalents thereof are inscribed as by being engraved, embossed, printed or otherwise afforded on this surface. 'In the present instance I have shown the fractional parts of an inch in increments of one sixty-fourth of an inch and in association with each such a fractional dimension the decimal equivalent thereof is provided, such decimal equivalent desirably being formed on the surface of the plate 3 in the same manner as that in which the fractions are formed or provided on such surface.

Moreover, in accordance with my invention, a representation of the extent of each such dimension is associated with each such fractional dimension. Thus, for example, where the frac: tional dimension eleven sixty-fourths is included on the plate 3, as indicated at 4, with the decimal equivalent thereof, indicated at 5, associated therewith on the plate 3, a groove 6 is formed on the surface of the plate 3 in association with the dimension eleven sixty-fourths inch, such groove 3 being eleven sixty-fourths of an inch in extent in this particular instance. By thus providing a groove 6 in association with, for example, the dimension eleven sixty-fourths inch, the magnitude or extent of this particular dimension may readily be determined on the instrument without resort to a graduated scale or the like.

In order to facilitate inscribing a circle, for example, of a diameter of eleven sixty-fourths inch, a notch 'I is formed along the groove 5 midway between the ends thereof so that one 3 element of a compass or divider may be disposed in this notch while the other element of such compass or divider is engaged with one or the other of the two ends of the groove 6 whereby the radius of a circle of a diameter eleven sixtyfourths inch is readily determined.

While in the preferred form of my invention I inscribe the fractional dimensions and the decimal equivalents thereof in the face of a. plate as 3, it will be understood that either the fractional dimensions or the decimal equivalents thereof could be omitted without departing from the ambit of my invention since the primary object of my invention is to afford, in an instrument of the aforesaid character, a representation of the various dimensions included thereon. Moreover, while I prefer to inscribe, in association with each such dimension, a representation of the extent of each particular dimension, it will be understood that fractional dimensions and the decimal equivalents thereof or the like may be embossed on the plate as 3 or otherwise being afforded thereon, and in such instance, therepresentation of the magnitude or extent of each particular dimension may be afforded on the plate in a manner like that in which the dimensions are afforded on this plate. Furthermore, in such instances, an indication of one-half the extent or other fractional part of each such dimension may be indicated on the representation of the extent of each such dimension by suitable indicia formed on the surface of the plate at the proper position along the extent of the representation of the particular dimension.

Modified form shown in Fig. 3

The modified form of my invention shown in Fig. 3 of the drawings is similar to that shown in Fig. 1 and like parts are indicated by the same reference numerals with the suffix a added thereto. Thus it will be seen that the form of my invention shown in Fig. 3 comprises a plate 3a on one face of which are inscribed fractional dimensions lia and the decimal equivalents 5a thereof. In a manner similar to that shown in Figs. 1 and 2, a representation 6a of the extent of each such dimension is associated with each such fractional dimension, the representations 6a in the modifled form of my invention shown in Fig. 3 having one end thereof abutting either the edge l0 or Il of the `plate 3 and extending inwardly therefrom at substantially right angles thereto.

The form of my invention shown in Fig. 3 is particularly well adapted to be used in stock rooms, machine shops, and the like, for determining the dimensions of articles, such as, for example, bolts, rivets and the like. For instance, it will be seen that if it is desired to determine the length of the shank of a particular rivet, the rivet may be placed on my device with the head thereof abutting the edge I0 or II of the plate 3a, depending on the size of the rivet to be measured, and the shank thereof extending inwardly across the face of the plate 3a perpendicularly to the edge against which the head is abutted. The rivet may then be quickly slid along the plate V3a. until the shank is aligned with a representation Ga which corresponds in length to the length of the shank, and the fractional or decimal dimension associated with that particular representation 6a may then be read. Rivets, bolts, and like articles are usually sized in increments of one thirty-second of an inch and, therefore, it will be apparent that my device shown in Fig.

3 wherein the dimensions vary by one sixty- 75 fourth of an inch may be readily used for the purpose of measuring such articles. However, it will be noted that I do not intend to limit my invention to a device embodying dimensions which vary in increments of one sixty-fourth of an inch and that devices may be constructed which embody dimensions varying in different increments without departing from the purview of my invention.

Also, like the form of my invention shown in Figs. 1 and 2, it will be noted that the form of `my invention shown in Fig. 3 embodies indicia la in the form of a notch midway between the ends `of each of the representations 6a whereby instruments such as dividers, Compasses and the like may be readily set, as previously described, to inscribe circles of a diameter equal to the length of the respective representations.

Modified form shown in Fig. 4

The vmodified form of my invention shown in Fig. 4 is substantially the same as that shown in Fig. 3, the principal difference being that the device shown in Fig. 4 is adapted to directly measure articles of a maximum length of two inches, whereas the device shown in Fig. 3 is adapted to directly measure articles of a maximum length of one inch.

Thus it will be seen that the modified form of my invention shown in Fig. 4 comprises a plate 3b on one face of which are inscribed fractional dimensions 4b and the decimal equivalents 5b thereof. A representation 6b of the extent of each such dimension is associated with each such fractional dimension and has a mid-point indicia Tb inscribed therein, the representations 6b extending inwardly from the edges Ib and IIb of the plate 3b in the same manner that the representations 6a extend inwardly from the edges ID and Il of the plate 3a. in the form of my invention shown in Fig. 3.

It will be noted that the dimensions shown in Fig. 4 vary in increments of one thirty-second of an inch rather than in increments of one sixtyfourth of an inch as shown in Fig. 3, but it will be remembered that my invention is not limited thereto and that dimensions varying by other increments can be used without departing from the purview of my invention.

Thus, while I have illustrated and described the preferred embodiment of my invention, it is to Ibe understood that this is capable of variation and modication and I therefore do not wish to be limited to the precise details set forth, but desire to avail myself of such changes and alterations as fall within the purview of the following claims.

1. In an instrument of the class described comprising a plate or the like having a plurality of dimensions afforded on one face thereof, a groove formed in said one face of said plate to afford a representation of the extent of each such dimension respectively and associated with such dimensions, andan indentation in the bottom of each groove along 'the extent thereof for indicating the radius of a circle of a diameter 'equal to the particular dimension.

2. In an instrument of the class described comprising a plate member having a plurality of dimensions afforded on one face thereof, a plurality of grooves formed in said one face of 'said plate to afford representations of the extent of each such dimension `and respectively associated with such dimension, each of said representations having one end positioned at the edge of said plate and the other end positioned inwardly therefrom, and indentations formed inthe bottoms of the respective grooves in proper position along the extent of each such representation for indicating the radius of a circle of a diameter equal to the particular dimension.

FRED P. HOPFELD.

REFERENCES CITED The following references are of record in the le of this patent:

Number 6 UNITED STATES PATENTS Name Date Sperry May 12, 1891 Ayer Apr. 15, 1902 Ablett Apr. 12, 1904 Hurley July 4, 1944 

